A porosity-based mechanics model for studying crack evolution from ITZ to mortar matrix in concrete

This study proposes a novel porosity-based mechanics model for investigating the crack evolution in concrete under uniaxial compression. This model accounts for the porosity gradient and heterogeneous mechanical properties within the concrete’s interfacial transition zone (ITZ). Validation against experimental results from the literature and international standards demonstrates the model’s accuracy in modeling both the global mechanical performance and crack evolution in concrete. Based on the proposed porosity-based mechanics model, a series of systematic studies are conducted to investigate the potential influence of ITZ mechanical properties, ITZ overlap effects induced by various aggregate volume fractions, and global tensile strength on the cracking mechanisms of concrete. Modeling results indicate that the crack evolution from ITZ to mortar matrix is significantly impacted by the ratio of ITZ to mortar mechanical parameters, and a correlation exists between the cracking proportions of the ITZ and the surrounding mortar. The ITZ overlap effect resulting from closely adjacent aggregates increases the susceptibility of the local mortar matrix to cracking. Increasing the overall tensile strength can reduce the cracking proportion of concrete, but it does not significantly affect crack evolution from ITZ to mortar matrix. Besides, increasing the concrete’s tensile strength significantly reduces tensile cracks in the mortar matrix, while having a limited effect on tensile cracks in the ITZ. Further results and detailed discussions are presented within the main text, hoping to provide new insights into the damage process of concrete under external loading.